


///
///   基础语法
///   基本语法可以参考  https://dart.cn/codelabs/dart-cheatsheet
///   列表相关操作可以参考  https://dart.cn/codelabs/iterables
///   异步操作可以参考  https://dart.cn/codelabs/async-await
///   空安全处理可以参考   https://dart.cn/codelabs/null-safety
///  Extension 方法可以参考 https://dart.cn/guides/language/extension-methods
///
///   开发技巧使用
///   异步操作 https://dart.cn/codelabs/async-await
///   Streams  https://dart.cn/tutorials/language/streams
///   json相关操作  https://dart.cn/guides/json
///  与其他语音调用  https://dart.cn/guides/libraries/c-interop     https://dart.cn/guides/libraries/objective-c-interop
///
///
void main(){


  const item = ["23123","abdsada","xczcxzx"];
  
  String data=item.singleWhere((element) => element.contains("a"),orElse:()=> "No Data");
  
  print(data);

 data == null ? throw Exception() : data.length;
}

